1. Field of the Invention
The present invention relates to a wireless transmission circuit, and more particularly to a wireless transmission circuit enabling modulation of radio frequency (RF) power amplification.
2. Description of the Prior Art
Various input devices for a computer system in the early stage, such as mouse, keyboard, joystick, track ball, etc., send their input data to the computer system via a data transmission interface, such as a serial port, a parallel port or a universal serial bus (USB). On receipt of the data input from the input devices, the computer system immediately performs corresponding actions.
With the quickly developed computer technologies, the peripherals of a computer system also involve in very high level of electronic technologies. The constant development of RF transmission technique enables many wireless input devices, such as wireless mouse, wireless keyboard, wireless joystick, etc., to become very popular in the markets. Since these wireless input devices are not able to obtain a working current source from the computer system via cables, they must have batteries mounted therein to obtain the required working current source.
To ensure normal usage of wireless devices, it is important for them to have a durable battery life. There is a close relation between the battery life and a consumed power of a wireless device. The wireless device would require different RF transmission powers at an output thereof depending on actual working conditions, such as a distance between a transmission end and a reception end, the material of surrounding working environment, etc. Moreover, the problem of RF interference becomes serious when the wireless devices become highly popular among users. All these problems should be taken into consideration when designing the wireless devices, in order to decrease the use of the battery and avoid mutual interference of RF signals.